Facebook said that it paid $2 billion for Oculus when the deal was announced in 2014.

At the center of Zenimax's suit against Facebook is Oculus CTO John Carmack, who previously ran a video game company within Zenimax called id Software and is best known as the mastermind behind video games like "Doom" and "Quake."

Zenimax has accused Oculus executives of knowingly stealing its software and trade secrets through the hiring of Carmack and five of his employees from id Software. It claims that Carmack violated his employee agreement with Zenimax by sharing confidential information that Oculus then used as the basis for its VR software. Additionally, Zenimax has accused Oculus cofounder Palmer Luckey of violating a non-disclosure agreement he signed with the publisher.

While in court on Tuesday, Zuckerberg denied having any knowledge of Carmack or Luckey violating their contracts through his acquisition of Oculus.

Zenimax lawyer Tony Sammi asked the Facebook founder how quickly the deal to buy Oculus was put together, and Zuckerberg revealed that Facebook's legal due diligence into Oculus's business was done over one weekend.

"Your plan was to begin legal diligence on Friday, and sign the deal on Monday?” Sammi asked Zuckerberg, according to Gizmodo.

“Yep,” Zuckerberg replied.

Zenimax is seeking $2 billion in damages against Facebook. Oculus cofounders Palmer Luckey and Brendan Iribe are scheduled to testify this week.